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EC number: 217-983-9
CAS number: 2031-67-6
Oral (OECD TG 401), rat: LD50 > 2007 mg/kg bw (limit test)
Dermal: (OCED TG 402), rat: LD50 > 2007 mg/kg bw (limit test)
Inhalation (OCED TG 403), rat, 4 h exposure: LC50 > 13500 mg/m³ (limit
It was not stated whether the tested concentration was the highest
achievable concentration, but taken into account the molecular weight
(178.3 g/mol) and the vapour pressure of the test substance (100 Pa at
25 °C and 1013 hPa) a saturated vapour concentration of 7190 mg/m³ (7.19
mg/L) can be calculated. It is therefore assumed that the tested
concentration was the highest achievable dose in the test atmosphere and
a higher exposure concentration is unlikely.
Table 1: Number of
Concentration and mortality per animals treated
Analytical Conc. (mg/L)
Table1. Number of
animals dead and with evident toxicity
Number with evident toxicity (/total)
Studies were chosen as key when the available study was of relevance and sufficient quality for classification, labelling and risk assessment. Other available data are included as supporting studies.
The key acute oral toxicity study which was conducted in compliance with GLP and according to the now deleted OECD TG 401, reports an LD50 value of >2007 mg/kg bw for triethoxy(methyl)silane. There were no mortality or marked systemic effect in rats at the limit dose of 2007 mg/kg bw (Hazleton France, 1992a). A supporting acute oral toxicity study conducted without compliance to GLP and similar to OECD TG 401 was also available on triethoxy(methyl)silane, which reported oral LD50 values of 7627 and 10057 mg/kg bw (dose given in mL/kg, converted using a relative density of 0.89), for males and females, respectively (Bushy Run Research Centre, 1981). A second supporting acute oral toxicity study conducted with triethoxy(methyl)silane according to OECD TG 423 in compliance with GLP reported a LD50 > 2000 mg/kg bw for female rats (METI, 2011). The results of all three experiments are in agreement with the low acute oral toxicity potential of triethoxy(methyl)silane.
The key acute inhalation toxicity study which was conducted in compliance with GLP and according to OECD TG 403 reports an LC50 of >13500 mg/m³ for triethoxy(methyl)silane vapour in rats after 4 hours. One animal from a total of ten died. The study reported that it was technically not possible to determine the particle size, presumably because the substance was emitted mainly as vapour. It was not stated whether the tested concentration was the highest achievable concentration, but taking into account that the measured concentration (13.5 mg/L) greatly exceeds the saturated vapour concentration (Hoechst, AG 1991). A limited report of an acute inhalation toxicity study without guideline compliance or GLP was also available, which reports one death in ten rats following a 6-hour exposure to the 'substantially saturated vapour’ of triethoxy(methyl)silane (Bushy Run Research Center, 1981). The exposed concentration was not given; however, this study further supports the lack of acute toxicity by the inhalation route of triethoxy(methyl)silane.
The key acute dermal toxicity study which was conducted in compliance with GLP and according to OCED TG 402, reports an LD50 value of >2007 mg/kg bw for triethoxy(methyl)silane. There were no mortality or marked systemic effect in rats at the limit dose of 2007 mg/kg bw (24 hour exposure) (Hazelton France, 1992b). A supporting acute dermal toxicity study which was not compliant with GLP but conducted in accordance with generally accepted scientific standards was also available, which reports an LD50 value of 11837 mg/kg (males) and >14240 mg/kg (females) (dose given in mL/kg, converted using a relative density of 0.89) (Bushy Run Research Center, 1981) thereby, further supporting the lack of acute toxicity potential by the dermal route of triethoxy(methyl)silane.
available data on acute toxicity of the registered substance do not meet
the criteria for classification according to Regulation 1272/2008 and
are therefore conclusive but not sufficient for classification.
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